Zen Vision:M has a lot more features(e.g., FM radio). Even if you don't need 30 gigs, you can partition the Hard Drive and use it as an external HD, which could come in handy. It is very easy to use with the scroll pad and all teh tactile buttons (although I have not used an iPod ever) - Sound quality is also great.
Of course, you may love teh scroll wheel, use iTunes, or want to use the player at the gym or just want something with less moving parts. If any of these last 3 then iPod I think is your choice. However, if you don't need the small size, don't use iTunes, and don't plan to use it in a way that takes advantage of the flash drive, then go for the Vision:M.
Although iPods have a lot of accessories, you may not need them. I bought a Boxwave skin, and an invisible sheild, and an audio/video out cable for my Zen, I really can't imagine what other accessories I would need.
Creative also has the ZenCast service going now, and has the Zen Organizer program so you can listen to "Zencasts" and other "podcasts" (of course, apple has this already)
Alright I know it's like comparing apples and oranges. First of all I'll I really want it for is music. The Nano 4GB should be all I need for me for my life but for only 50 more bucks I can get a zen vision m. To me this may be worth it, but I just can't decide. Also this will be my first mp3. I've read review after review and I know the zen:m sounds pretty good. I'm looking for ease of use to. I was hoping that maybe someone would have an opinion for me.